Internal combustion hammer



Oct. 10, 1939. F. N. BARD INTERNAL GOMBUSTION HAMMER Filed March.l2, 1937 '2 Sheets-Sheet 1 Oct. 10, 1939. F. N. BARD 2,175,736

INTERNAL COMBUS T I ON HAMMER Filed March 12, 1937 2 Sheets-Sheet 2 5i gli '11 V i g s I 50 j 1 l l *i f s@ l' r/ "/r /f @i Z5 Patented Oct. 10, 1939 UNITED STATES INTERNAL COMBUSTION HAMTVIER Francis N. Bard, Highland Park, Ill., assignor to Gas Tool Patents Corporation, a corporation of Delaware Application March 12, 1937, Serial No. 130,574

8 Claims.

This invention relates to an internal combustion hammer, and more particularly to an improved fuel tank therefor.

One feature of this invention is that it pro-- vides a relatively light fuel tank; another feature of this invention is that the tank is readily and cheaply manufactured and installed; yet another feature of this invention is that the tank may be of worked rather than cast metal; other features and advantages of this invention will be apparent from the following specification and the drawings, in which- Fig. l is a partial side elevation of a hammer having thereon a fuel tank embodying this invention; Fig. 2 is a transverse view, partly in section, along the line 2 2 of Fig. l; Fig, 3 is a partial elevation, partly in section, of a modified form; Fig. 4 is a sectional View along the line 4-4 of Fig. 3; and Fig, 5 is a View of another modification.

The internal combustion hammer on which this tank is illustrated is here shown as of the type having a piston freely reciprocable in a cylinder and adapted to impart impacts to a tool carried by the hammer. The hammer operates on the familiar two-cycle internal combustion principle, the piston compressing a charge beneath it on the down-stroke and transferring this charge to the combustion chamber above it for further compression and subsequent firing on the lip-stroke.

The general operation of this hammer forms no part of the present invention, and will not be further described here. Reference may be had to Mould Patents 1,782,740 and 1,997,072 for such general features,

It has heretofore been common in such free piston hammers to employ a fuel tank of a light cast metal, such as aluminum. It is of course desirable to keep the weight of the tank as low as possible, since the entire weight of the hammer must be kept within limits to provide easy handling by the operator. The hammer is, however, subject to extreme vibration and attendant troubles thereto when in use. The vibration causes fatigue and attendant fracture of metal parts which are too light, and this factor provides a limitation on the lightness of a cast tank. Thus cast tanks were generally heavier than desirable, and had reinforcing ribs cast therein.

The present invention provides a fuel tank with equivalent capacity to those now known in the art, good heat dissipation, sufficient strength to withstand vibration and rough handling of the hammer, and yet enables the tank to be con- (Cl. 12S-7) structed of worked metal, such as rolled or drawn steel.

In the particular embodiment of this invention illustrated herewith in Figs, l and 2, the hammer IB comprises a cylinder II, an anvil housing 5 I2 therebeneath, and a handling bracket I3 thereabove. Tie rods I4 serve to hold the three previously mentioned parts in one operative unit. In accordance with conventional practice, a piston hammer, not shown, is reciprocated within the cylinder and a sub-piston compression space is provided in the lower part of the cylinder and anvil housing, and a combustion space in the upper part o-f the cylinder. A timer l5 and spark plug I 6 are operatively connected in known manner to ignite the charge in the combustion space.

The charge-forming device for furnishing the cylinder with a combustible charge is here shown as a fuel tank Il, a carburetor I8, and an air intake I9. The carburetor is of the simple type shown in Fig. 4 of Mould Patent No. 1,997,072, wherein liquid fuel, such as gasoline, is fed through a narrow orifice to air passing through an opening into which the orice leads when a Valve member is raised by suction existing within the engine or hammer.

The fuel tank is here shown as comprising a spirally wound portion or tube 20 of worked metal and an expanded portion 2 I` The spiral portion includes a plurality of turns of tube wound'about the lower part of the cylinder and the anvil housing, but spaced therefrom. The expanded portion 2l, as may be better seen in Fig. 2, is substantially kidney-shaped in cross-section, so that it provides relatively large volume without either contacting the hammer or projecting too far therefrom. Abo-ve the expanded portion a short vertical tube or neck 22 provides a filling opening, and is closed with a cap 23 when the hammer is in use. Both tubes are welded or otherwise permanently fastened in the expanded portion 2l. It will be noted that the tube 20 is carried at its lower end by the carburetor I8, bolted in turn to the anvil housing I2, and at its upper end by a supporting member 24 fastened to the handle bracket I3. This latter bracket, of course, extends completely across the top of the cylinder, and the tank may -be supported therefrom at any desired place.

The particular construction and arrangement described above provides a fuel tank of worked metal which is strong, relatively free from fatigue troubles due to Vibration, and so supported that the fuel therein is kept coolI Not only does a spirally Wound tube provide a large heat dissipation surface for a given volume, but also the way in which it is spaced from the cylinder and supported from the anvil housing and handle bracket prevent ready transfer of heat thereto from the cylinder. A large surface for heat dissipation, of course, results in a lower temperature of the fuel within the tank, which obviates troubles frequently encountered in such hammers by boiling of the fuel. In addition to the substantial cooling effect provided by the spirally wound tube, this tank gives a uniform distribution of weight with respect to the hammer.

In the particular embodiment of this invention shown in Figs. 3 and 4, the tube 25, cornprising a spirally wound portion, is carried straight on up to the filler cap, and is surrounded through its vertical portion with a seoond pipe or expanded portion enclosed at its top and bottom and welded or otherwise fastened to the tube 25. This latter tube has therethrough, near the top of the expanded portion 26, openings 21, and near the bottom portion similar openings 28. These enable free flow of the gasoline or other liquid fuel from the tube to the expanded portion and vice versa. While this does not provide quite as much volume in the expanded' portion as the previously described modification, it is of simple and rugged construction and has been found to provide a good fuel tank for such a hammer.

It is to be understood, of course, that it is not necessary to employ an expanded portion in connection with the spirally wound tube shown herein. The modification illustrated in Fig. 5 shows the tube 29 extending upwardly in a straight vertical portion to the ller cap 30 near the top of the hammer. The desired tank volume may be achieved by choosing a tube of slightly larger iameter than in the other modifications, or by adding another turn or two to the spirally wound portion.

While I have shown and described certain embodiments of my invention, it is to be understood that it is capable of many modifications. Changes, therefore, in the construction and arrangement may be made without departing from the spirit and scope of the invention as disclosed in the appended claims.

What I claim as new and desire to secure by Letters Patent is:

i. Apparatus of the character described for supplying a combustible charge to the cylinder of an internal combustion percussive hammer having a piston reciprocable therein, including: a fuel tank adapted to contain a fluid fuel, said tank comprising a metal tube as a substantial portion thereof, said tube having a portion thereof spirally wound about said hammer but spaced therefrom.

2. Apparatus of the character described for supplying a, combustible charge to the cylinder of an internal combustion percussive hammer having a piston reciprocable therein, a handle bracket thereabove, and an anvil housing therebeneath, including: a fuel tank adapted to contain a liquid fuel, said tank comprising a worked metal tube having a portion thereof spirally wound for a plurality of turns about said hammer but spaced therefrom, said tube being supported from said bracket and housing.

3. Apparatus of the character described for supplying a combustible charge to the cylinder of an internal combustion percussive hammer having a piston reciprocable therein, including: a fuel tank adapted to contain a fluid fuel, said tank comprising a spirally wound worked metal tube having an expanded portion.

4. Apparatus of the character claimed in claim 2, wherein said tube has an expanded portion at one end of the spirally wound portion thereof.

5. Apparatus of the character claimed in claim 3, wherein said expanded portion is substantially kidney shaped in cross section.

6. Apparatus of the character claimed in claim 3, wherein said expanded portion comprises a second tube surrounding said rst mentioned tube and communicating therewith through openings therein.

'7. Apparatus of the character described for supplying a combustible charge to the cylinder of an internal combustion percussive hammer, including: a fuel tank adapted to contain a liquid fuel, said tank comprising a relatively thin metal tube having a major portion thereof spirally wound in a plurality of turns about said hammer and substantially concentric therewith.

8. Apparatus of the character described for supplying a combustible charge to the cylinder of an internal combustion percussive hammer having a piston reciprocable therein, including: a fuel tank adapted to contain a fluid fuel, said tank having as a substantial portion thereof a thinwalled tube of relatively small diameter and considerable length, said tube being so arranged as to have a plurality of convolutions therein.

FRANCIS N. BARD. 

